His titular position is Patriarch of the Orthodox Church of Constantinople, one of the sixteen autocephalous Churches, and he is one of the original four Eastern Orthodox patriarchs. In his role as head of the Orthodox Church of Constantinople, he additionally holds the title Archbishop of Constantinople and New Rome. He should not be confused with the Latin Patriarch of Constantinople.
As Constantine the Great had made Byzantium "New Rome", its bishop, once the humble suffragan of Heraclea, thought that he should become second only, if not almost equal, to the Bishop of Old Rome. For many centuries the popes opposed this ambition, not because any one thought of disputing their first place, but because they were unwilling to change the old order of the hierarchy. In 381 the First Council of Constantinople declared that: "The Bishop of Constantinople shall have the primacy of honour after the Bishop of Rome, because it is New Rome" (can. iii).
The popes (Damasus and Gregory the Great) refused to confirm this canon. Nevertheless Constantinople grew by favour of the Byzantine emperor, whose centralizing policy found a ready help in the authority of his court bishop.
The Council of Chalcedon in 451 established Constantinople as a patriarchate with jurisdiction over Asia Minor and Thrace and gave it the second place after Rome (can. xxviii). Pope Leo I refused to admit this canon, which was made in the absence of his legates; for centuries Rome still refused to give the second place to Constantinople. It was not until the Fourth Lateran Council in 1215 that the Latin Patriarch of Constantinople was allowed this place; in 1439 the Council of Florence gave it to the Greek patriarch. Nevertheless in the East the wish of the Byzantine emperor was powerful enough to obtain recognition for his patriarch; from Chalcedon we must count Constantinople as practically, if not legally, the second patriarchate.
After the fall of Constantinople, the Ottoman Sultan claimed the right of appointment, but the modern Turkish state simply requires the Patriarch to be a Turkish citizen, and allows the Orthodox church to elect him.
The current Patriarch is Patriarch Bartholomew I.